With no system fans active, adding a second HD 4870 in CrossFireX
increased the CPU and GPU temperature by about 5°C, while the Southbridge,
trapped between two 130W+ graphics cards, heated up by an extra 10°C. The
noise level was also a tremendous 10~11 dBA higher. This time, turning on the
system fans resulted in a decrease in noise as the side fan helped to cool the
GPUs and areas surrounding them, so their fans didn't have to work as hard.
With all the fans running at 9V, the CPU temperature dropped by 11°C and
the Southbridge temperature was 17°C lower. The two graphics cards ran moderately
cooler as well, resulting in a decrease in fan speed and an overall system noise
reduction. Increasing the fan speed to 12V made the system 1~2 dBA louder with
very little thermal improvement except for the Southbridge.

The system measured 30 dBA@1m with the CrossFireX configuration.

Like the single GPU setup, the overall acoustics of all the configurations
tested had a smooth character, but was very loud.

The advantage of having a large side fan blowing on the video cards became
evident when we tested the case using a CrossFireX configuration. The Maelstrom
runs cooler than the Antec 1200
in all respects except for the hard drive as we did not turn on the front fan.
It was also 1~2 dBA quieter due to lower GPU fan speeds. Neither come close
to the Raven 2 though, which remains tops for the moment.